CodeXOBD

P0141 — O2 Heater Circuit Malfunction (Bank 1 Sensor 2)

P0141 means the heater circuit in the downstream oxygen sensor is not working. The sensor will still function once hot from exhaust gas, but cold-start monitoring will be delayed.

Low

The engine runs normally. Converter efficiency monitoring is delayed on cold starts.

$20–$200Parts, typical range
0.3–1 hLabour
estimateNot a quote · 2026 basis

What P0141 means

P0141 is the downstream equivalent of P0030. The module monitors the heater current in the post-catalytic-converter oxygen sensor. When current is outside the expected range, P0141 sets. The heater brings the sensor to operating temperature within seconds of a cold start; without it, the sensor relies on exhaust heat alone, which takes much longer.

Technical summary
SystemEmission control
How the catalytic converter is gradedExhaust leaves the engine, passes the upstream oxygen sensor, then the catalytic converter, then the downstream oxygen sensor. The module compares the two sensor signals: on a healthy converter the downstream signal is steady while the upstream one oscillates. When the downstream signal starts to mirror the upstream one, the converter is judged to have stopped storing oxygen.Engineexhaust outUpstream O₂sets fuel trimCatalytic converterstores oxygenDownstream O₂grades the converterThe module compares the two sensors — that comparison is the test

Symptoms you may notice

What causes P0141

Downstream O2 sensor heater has failed

Very likelylow costeasy

The internal heater element has burned out, which is the most common cause on sensors past 100,000 km.

Wiring or connector fault

Likelylow costeasy

Heat from the exhaust pipe damages the harness over time.

Blown fuse for downstream O2 heater

Possiblelow costeasy

Check the fuse before replacing the sensor — a shorted sensor may have blown it.

How to diagnose it

1

Check the heater fuse

Inspect the fuse for the downstream O2 heater circuit. If blown, check for a short before replacing.

Tools: Fuse pullerIf it passes: Fuse is intact. Continue to step 2.If it fails: Replace the fuse. If it blows again, the sensor or wiring is shorted.
2

Measure heater resistance

Disconnect the sensor and measure resistance across the heater terminals.

Tools: MultimeterExpected: 4-40 ohmsIf it passes: Resistance is in range. Check the wiring.If it fails: Open or shorted — replace the sensor.
3

Check voltage supply to the heater circuit

With the sensor disconnected, turn the ignition on and measure voltage at the heater power wire in the harness connector. It should read battery voltage. If there is no voltage, trace the circuit back to the fuse and relay.

Tools: MultimeterIf it passes: Battery voltage is present at the connector. The sensor is confirmed faulty.If it fails: No voltage — check the fuse, relay, and wiring for an open circuit.

Related codes

P0030P0136

Common questions

Can I ignore P0141?

The engine will run fine, but the converter monitor cannot run on cold starts. In an emissions test jurisdiction, this alone can cause a failure.

Last verified 2026-07-27 · Sources: SAE J2012 — Diagnostic Trouble Code Definitions and Failure Type Byte (SAE International)

This information is for general guidance and is not a substitute for professional diagnosis. Cost figures are estimates, not quotes.